Driving unit for speakers



' April 22, 1930. N. M. MICHAILOVSKY DRIVING UNIT FOR SPEAKERS Filed Aug. 23. 1928 Patented Apr. 22, 1930 UNITED STATE FATE NICHOLAS M. MICHAILOVSKY, OF BRONX, NEW YORK, ASSIGNOR BY DIRECT AND MESNE ASSIGNMENTS, OF THIRTY-SEVEN AND ONE-HALF PER CENT TO PAUL NOEL BITTER, OF LONG ISLAND, NEW YORK, AND TWENTY-FIVE PER CENT TO HENRY W. BOETTGER, OF NEW YORK, N. Y.

DRIVING UNIT FOR SPEAKERS Application filed August 23, 1928. Serial No. 301,526.

This invention relates to the motor or driving unit construction of loud speakers and the like and special objects of the invention are to provide a motor or unit of this charac ter, which will be of simple, inexpensive rugged construction and which will be sensitive and at the same time powerful in its action.

The drawing accompanying and forming part of this invention illustrates some of the commercial forms the invention may take, but it should be understood that the actual structure may be modified as regards the present disclosure without departure from the true spirit and broad scope of the invention.

Fig. 1 in the drawing is a front or face View and Fig. 2 is an end or bottom view of the unit, the driving rod being indicated as broken, for lack of space; Fig. 3 is a detached perspective View of the armature; Figs. 4 and 5 are broken detail views illustrating a modified form of armature and pole construction.

The magnet which may be either of permanent or the electromagnetic type, is indi cated as having a U-shaped yoke 7 having rectangular shaped end portions, to the opposite sides of which pole pieces 88 and 99 are secured by through screws 10. The pole pieces of the opposing sets are shown as tapered toward each other and as sepa rated at the ends by the magnetic gaps 11.'

At their inner faces the pole pieces are shown as curved on arcs 12 struck from a center 13, which corresponds to the actual center between the two gaps.

The armature is shown as consisting of a relatively light bar 14 of magnetic material of rectangular cross-section pivoted midlength at the center 13 on pin 15 and having side wings 16 at the ends of the same curved to the shape of the inside pole faces and operating with close clearance inside said faces. These arcuate end portions of the ar mature may be as wide or slightly wider than the magnetic gaps and are shown as extending the full length of such gaps, so as to reduce the magnetic reluctance across the gaps.

The armature is magnetized in the illustration by coils 17 about the ends of the armature and shown as supported in said posi tions against the inner faces ofthe pole pieces by an intermediate non-magnetic bridge 18 secured by screws 19 to the ends of the magnet yoke and having seats or recesses 20 in its opposite sides receiving the coils. This is a desirable construction for manufacturing purposes as the parts are secured together in their proper relation by the simple act of assemblage. Thissame bridge piece may also carry the pin or mounting 15 for the armature, as indicated, so that all parts of the unit may be properly co related by simply arranging them in order and fastening the pole pieces and bridge securing screws.

A suitable impulse transmitting connection may be provided, such as the rod 21 shown engaged with the armature at a point between the pivotal support at one end of s the same and asextending from such point straight out through a passage 22 in the adjacent side of the yoke.

If desired, the transmission connection may be brought out from the end of the ar;

mature, outside the magnet structure as shown at 21 in Figs. 4: and 5, where, for the purpose, the armature is shown as having a narrow rib 23 extended beyond the arcuate polar portion of the same, to which the rod is connected and which operates freely in notches 24; formed in the opposing edges of the pole pieces. This rib by its movement in the notches contributes to the magnetic interaction between the armature and pole pieces, strengthening the action to that extent.

By the pivotal or rotational movement of the armature and the corresponding shaping of the armature and pole pieces, constant clearance is maintained and by making the curved armature wings as long and as wide as the gaps and opposed to the thinned tip ends of they curved pole pieces, where the flux is strongest a powerful starting action is ob tained, which continues throughout the range of movement, rendering the unit sensitive to the smaller impulses and relatively powerful in its operation. I

The bridge18 is shown as having a trussed or arched portion 18 extending up between the pole pieces and providing a hearing or support for the upper end of the armature supportingvpin or member 15. This helps to keepthearmature operating truly between 5 the pole pieces with a minimum clearance.

The magnet structure may be of the single .p0le as Well as of the bi-polar type illus- .trated.

What isclaimed is:

1. A driving unit for speakers or the like, comprising a magnet having pole pieces fixed over opposite faces of the same and separated to provide magnetic gaps at the opposite sides of the magnet, theinside faces ofsaid pole pieces being curved substantially as, arcs having a center between the magnetic gaps,

an armature mounted for rotational movement about a corresponding center on an axissubstantially parallel with and extending in the general direction of length of the magnet, said armature extending transversely across from one face toward the opposite face of the magnet and having polar portions shaped similarly to and opposed to the curved inside faces of the pole pieces, a transmission connection extending from said armature and magnetizing means for the armature.

, 2. A construction as in claim 1, in which the magnetizing means consists of two coils supported about the opposite end portions of the armature and in which said coils are sup- 7 ported by a bridge member against the inside faces of the pole pieces.

V 3. A driving unit for speakers or the like,

comprising a magnet yoke, pole pieces extending toward each other from the ends of the magnet yoke to provide magnetic gaps at opposite faces of the yoke, an armature extending transversely from one magnet face 0 toward the opposite magnetface, said armature being supported intermediate its ends between the pole pieces for rocking motion in the direction of extent across the magnetic I gaps, magnetizing coils surrounding theopposite end portions of the armature and a power transmission connection extending from the armature.

4. A driving unit for speakers or the like, comprising a magnet yoke, pole pieces extendingtowardeach other from the ends oi. the magnet yoke to provide magnetic gaps at opposite faces of the yoke, an armature supported intermediate its ends between the pole pieces for rocking motion in the direction of extentacross the magnetic gaps, magnetizing coils surrounding the opposite end portions of the armature, a power transmission connection extending from the armature be tween the point of support on the armature 69 and one of its endsitoward one side of the yoke,-said yoke having a passage insaid side for said transmission connection.

In testimony whereof I afiix my signature.

:NICHQLAS M. MIGHAILOYSKY. 

